The present invention relates to a fire bolt assembly and, more particularly, to a fire bolt assembly preventing opening of a door when exposed to a fire.
It is known to mount a fire bolt assembly in a door (often referred to as a fireproof door) for automatically locking the door in a closed state when a fire occurs, preventing flowing of smoke and fire from one side of the door to the other side. In an approach, a fire bolt assembly includes a receiving tube mounted in a door, a positioning bolt received in the receiving tube and biased by a spring received in the receiving tube, and a stop member secured in an opening of the receiving tube for maintaining the positioning bolt in the receiving tube. The stop member is made of plastic material having a melting point of about 250-350° C., which is lower than those of the receiving tube, the positioning bolt, and the spring. The positioning bolt is moved out of the receiving tube and engaged with an engaging hole in another door or a door frame when the stop member melts due to the heat of the fire, allowing locking of the door in the event of a fire. However, the stop member has a skirt that is completely received in the receiving tube so that a considerable portion of the melted stop member may remain in the receiving tube and hinder the positioning bolt from moving out of the receiving tube after the stop member has melted, resulting in failure of the locking function of the positioning bolt.
Thus, a need exists for a fire bolt assembly for a door which is capable of preventing the door from being opened when exposed to a fire while allowing easy assembly of the fire bolt assembly.